Puncturable catheter

ABSTRACT

A catheter provided with a guidewire catheter lumen having a thin covering that is easily punctured by a guidewire at virtually any desired point along the catheter length. The thin covering may be integral with the catheter shaft, or may be a separate component that covers only the portion of the catheter shaft immediately adjacent the outer portion of the guidewire lumen, or may be a thin tubular construct that surrounds the entire catheter shaft. The covering is preferably relatively translucent, allowing for good visualization of the location of the end of the guidewire to enable puncturing of the covering at the desired location along the length of the catheter shaft. The covering is also preferably tear resistant at puncture sites. The catheter shaft is preferably made of a material having a color that provides good visibility against an operating field, and more preferably is phosphorescent either entirely or in part. Materials suitable for the catheter shaft are polymeric materials well known in the art; the catheter shaft may optionally be provided with metallic stiffening components such as wires or hypotubes along all or part of the catheter length.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of application Ser. No.10/346,977 filed Jan. 17, 2003 now abandoned.

FIELD OF THE INVENTION

The present invention relates to the field of catheters for use withguidewires, and more particularly to such catheters intended for thedelivery of a therapeutic agent or device.

BACKGROUND OF THE INVENTION

A variety of different therapies can be delivered within the human bodyby catheter devices. Therapeutic devices such as dilation balloons,stents, and embolic filters, and therapeutic agents such as drugs andradiation sources, may be positioned at or near the distal end of thecatheter for delivery to a desired site within the body. The proximalend of the catheter is considered to be the end that remains outside ofthe body, manipulated by the medical practitioner.

To aid in positioning of the distal end of the catheter within the body,typically the distal end of a guidewire is first navigated to thetreatment area. After the guidewire has been positioned, the wire canthen be used to guide the distal end of the catheter into place.Additionally, a guide catheter may be used to further facilitate thepositioning of the guidewire and/or delivery catheter. The interactionbetween the guidewire and the catheter is critical, as the physicianneeds to easily track the distal end of the catheter along the path ofthe guidewire. A number of interaction issues can arise, including butnot limited to, having to use more than one person, having to use a longwire, having the advancement of the catheter affect the position of thewire, having the catheter not able to track the wire through tortuousanatomy, having excessive friction between the catheter and the wire,and having a difference between the amount of axial motion applied tothe proximal end of the catheter and the amount of axial movement at thedistal end of the catheter.

In various attempts to address these issues, a number of catheterdesigns have been introduced that have defined the interaction betweenthe guidewire and the catheter. Two of the primary applications ofcatheter systems are percutanous transluminal coronary angioplasty(PTCA) and coronary stent delivery. Two main types of catheter designs,over-the-wire (OTW) and rapid-exchange (RX), dominate theseapplications. Each of these designs has its advantages anddisadvantages. OTW catheters track over their entire length on aguidewire, which allows them to follow the wire easily and allows thedirect transmission of longitudinal force over the guidewire.Additionally, these catheters allow for guidewires to be exchanged oncethe catheter has been advanced into position, which may be desirablewhen different guidewire attributes (e.g., tip curvature or radiopaquemarkers) are needed. However, these systems require the use of a longguidewire (e.g., 300 cm in length) and cannot be effectively operated byone person.

RX catheters typically use shorter guidewires (e.g., 180 cm in length)which allow the catheter to be operated by a single physician. Thephysician is able to hold the guide catheter and guidewire with one handwhile using his other hand to advance or retract the catheter along theguidewire. However, because the entire length of the RX catheter doesnot slide over the guidewire, the direct transmission of longitudinalforce along the path of the guidewire may be compromised, and wireexchange can not be performed once the proximal catheter guidewire portis advanced into the patient.

Among various catheter designs intended for stent delivery is a systemtaught by U.S. Pat. No. 5,534,007 to St. Germain et al. This systemincludes a tubular exterior sleeve with an adjustable length sectionthat, under axial compression, shortens via corrugations to causeanother sleeve at the distal end of the catheter to be withdrawn in aproximal direction, releasing the stent. The overall length of thecatheter remains the same during the axial compression of the exteriorsleeve, and in particular, the length of the guidewire lumen is notadjustable.

U.S. Pat. Nos. 5,334,147 and 5,380,283 to Johnson teach the constructionof a balloon catheter having a proximal portion that includes anaperture through the wall of the catheter into the guidewire lumen. Theaperture is covered by a frangible wall (e.g., a thin-walled tube sealedto the catheter body in a position to cover the aperture portion). Thefrangible wall may be punctured by a guidewire, allowing the guidewireto exit the catheter guidewire lumen via the aperture.

U.S. Pat. No. 5,472,425 to Teirstein describes a catheter having aguidewire lumen covered by a rupturable membrane that extends alongsubstantially the entire length of the catheter, whereby the membranemay be intentionally punctured at any desired location by the guidewire.The use and general construction of the catheter are related, althoughno materials or specific constructions for the rupturable membrane aretaught.

SUMMARY OF THE INVENTION

The present invention relates to a catheter provided with a guidewirecatheter lumen having a thin covering that is easily punctured by theback end (i.e., the proximal end) of a guidewire at virtually anydesired point along the catheter length. The thin covering may beintegral with the catheter shaft, or may be a separate component thatcovers only the portion of the catheter shaft immediately adjacent theouter portion of the guidewire lumen, or may be a thin tubular constructthat surrounds the entire catheter shaft. The covering is preferablyadequately translucent to allow for good visualization of the locationof the back end of the guidewire in order to enable puncturing of thecovering at the desired location along the length of the catheter shaft.The catheter shaft is preferably made of a material having a color thatprovides good visibility against an operating field, and more preferablyis luminous or phosphorescent either entirely or in part. Materialssuitable for the catheter shaft are polymeric materials well known inthe art; the catheter shaft may optionally be provided with metallicstiffening components such as wires, wire braids or hypotubes along allor part of the catheter length.

In a preferred embodiment, the thin covering is made from a thin tape ofporous expanded polytetrafluoroethylene (ePTFE) helically wrapped aboutthe exterior of a catheter shaft. Most preferably, the wrapping isaccomplished in two opposing directions parallel to the length of thecatheter shaft, resulting in a bias-ply construction. This thin coveringoffers good transparency and is easily punctured by the end of aguidewire, and yet is resistant to tearing at the puncture site.

Other materials may be used for the puncturable thin covering, includingpolyethylene terephthalate (PET). These materials may also offer goodtranslucency, but may be less tear resistant than the helically wrappedePTFE thin coverings.

The thin covering (either integral with the catheter shaft or a separatecovering) may optionally be provided with a multiplicity of small,pre-formed openings through the thickness of the covering to allow forpassage of the back end of a guidewire through any of these openings.The openings would preferably be arranged in a single line extendingdirectly above the guidewire lumen.

The thin covering may optionally be in the form of a braid orhelically-wound filaments that allow the guidewire to be passed throughany of the multiplicity of openings or interstices that exist betweenadjacent filaments of the braid or winding. The braid or winding may beof either various polymeric or metallic materials. The braid or windingmay be exposed around the entire exterior of the catheter shaft oralternatively may be exposed over only the side of the guidewire lumenclosest to the exterior of the catheter shaft.

For many embodiments, the guidewire lumen is in the form of a slot madeinto the catheter shaft, with the slot provided with the thin covering.Preferably, the slot extends for most or even all of the length of thecatheter shaft. It may optionally extend through a balloon or otherdevice located at the distal end of the catheter. The slot is coveredwith by a thin tubular covering that coaxially encloses the entirecatheter shaft or alternatively a strip of thin tape-like coveringmaterial that covers the slot and is adhered to the surface of thecatheter shaft immediately adjacent both sides of the slot. Amultiplicity of pre-formed openings may be provided through the thincovering as noted above. Also as noted above, the slot covering materialmay take the form of a braid or winding of filaments. This braid orwinding of filaments may optionally be covered with a thin polymerictube except for the filaments immediately over the top of the slot whichpreferably remain exposed and allow for passage of the end of aguidewire through any interstice between adjacent filaments.

Other embodiments using the catheter shaft may be provided with apuncturable tubular form inserted into the slot. This tubular form maybe made with filaments braided into the tubular form, or a tubular formmade of helically wound filaments or from a thin polymeric material,with the tube having an inside diameter adequately large to accommodatea guidewire of the desired size. These tubes are fitted and secured intothe slot formed into the catheter shaft, with the result that the outersurface of the braided or helically wound tube covers the exposed partof the slot and allows for the back end of a guidewire contained withinthe tube to be passed through any interstice between adjacent filamentsof the braided or helically wound tube. When the tubular form is madefrom the thin polymeric material, the resulting tube inserted into thecatheter shaft slot is puncturable at any desired location by the backend of a guidewire.

In addition to being puncturable by the back end of the guidewire, theguidewire catheter lumen may optionally be made to be adjustable inlength. The adjustable length catheter guidewire lumen is the conduit,or catheter, or tube, or space that contains the guidewire or provides aspace for the passage of a guidewire therethrough. The space may beadjustable in length, as will be further described.

By adjustable length is meant that the length of the adjustable lengthguidewire catheter lumen may be changed by the application of easilyapplied manual axial force. In its axially extended or fully lengthenedstate, the adjustable length guidewire catheter lumen is at least 10%longer than when in the axially compressed, fully shortened state. Morepreferably, the adjustable length guidewire catheter lumen is adjustableby an amount of at least about 20%, or 30%, or 40%, or 50%, or 75%, or100%, or 200%, or 400%, or 1000%, or 2000%.

The adjustable length guidewire catheter lumen is adjustable in lengthby virtue of being scrunchable. This means that this tubular componentis easily shortened in length under axial force, without telescoping asby the successive sliding of overlapped concentric tubular sections.Various means of providing a scrunchable tube for use as the adjustablelength guidewire catheter lumen include the provision of corrugations(i.e., wrinkles, or accordion pleats or folds), or by the use of aporous tube that compresses axially by reduction in total void space.These are further described below.

Suitable materials for the adjustable length lumen include ePTFE,polyethylene terephthalate (PET), polyamide, or other thermoplastic orthermoset polymers, or other such relatively inelastic materials.Alternatively, an elastomeric material may be used for the adjustablelength lumen, which materials elongate by the application of anextending axial force. The term “elastomeric” is intended to describe acondition whereby a polymer displays stretch and recovery propertiessimilar to an elastomer, although not necessarily to the same degree ofstretch and/or recovery.

The ability of the catheter to be punctured by the back end of aguidewire at any desired location along the length of the puncturablesection of the catheter allows the catheter assembly to be usedeffectively as desired in either OTW or RX mode.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A shows a longitudinal cross section of a catheter having apuncturable guidewire lumen covering.

FIG. 1B shows a longitudinal cross section of the catheter of FIG. 1A inuse with the catheter, the guidewire having punctured the puncturableguidewire lumen covering.

FIGS. 1C and 1D show transverse cross sections of the catheter of FIG.1B with the guidewire within and without the puncturable section.

FIG. 1E shows a longitudinal cross section of a catheter that is avariation of the design shown in FIGS. 1A and 1B wherein the guidewireoperates in a slot provided in the exterior wall of a lumen of thecatheter.

FIGS. 1F, 1G and 1H show transverse cross sections taken at threedifferent locations along the length of the catheter shown in FIG. 1E.

FIG. 2A shows a perspective view of a preferred slotted catheter shaft.

FIG. 2B is a perspective view of the preferred slotted catheter shaft ofFIG. 2A provided with a helical wrap of a polymeric tape that forms apuncturable thin cover over the slot.

FIG. 2C is a perspective view of the preferred slotted catheter shaft ofFIG. 2A provided with a puncturable thin cover in the form of a thintubular sheath.

FIG. 2D is a perspective view of the catheter shaft of FIG. 2C whereinthe thin tubular sheath is formed by a cigarette wrap.

FIG. 2E is a perspective view of the preferred slotted catheter shaft ofFIG. 2A provided with a puncturable thin cover in the form of a strip ortape of a polymeric material adhered over the surface of the cathetershaft immediately adjacent to both sides of the slot.

FIG. 2F is a perspective view of an alternative embodiment wherein thepuncturable guidewire lumen covering is integral with the cathetershaft.

FIG. 2G is a perspective view of an alternative embodiment wherein thethin cover over the guidewire lumen is provided with a multiplicity ofpre-formed openings which allow passage of the back end of a guidewirethrough any opening chosen by the user.

FIGS. 3A-3C are transverse cross sectional views showing variations ofthe embodiment described by FIG. 2E

FIG. 4A is a perspective view of the preferred slotted catheter shaft ofFIG. 2A provided with a puncturable thin cover in the form of a braid.

FIG. 4B is a perspective view of the braid-covered catheter shaft ofFIG. 3A further provided with a thin exterior tubular sheath over thebraid.

FIG. 4C is a perspective view of the braid-and-sheath covered cathetershaft of FIG. 3B wherein the portion of the sheath covering the catheterslot has been removed.

FIG. 4D is a perspective view of catheter shaft with an alternativebraid-covered slot wherein a braided tube is fitted and secured into theslot.

FIG. 4E is a variation of FIG. 4A wherein the braided tubular cover isreplaced with a helically wound tubular cover.

FIG. 4F is a variation of FIG. 4D wherein the braided tube is replacedwith a helically wound tube.

FIG. 4G is a variation of FIGS. 4D and 4F wherein the tubular cover ismade from a thin polymeric material.

FIG. 5 shows a longitudinal cross section of a basic embodiment of thecatheter of the present invention, without a y-fitting but including ahub on the proximal end of the inflation lumen, a puncturable adjustablelength guidewire catheter lumen (shown in its axially compressed orshortened state) located distal to the hub and a tubular slider forcontrolling the proximal end of the adjustable length lumen.

FIG. 6 is a perspective view of a tool useful for bending of thecatheter shaft during puncturing of the thin puncturable cover by theback end of a guidewire.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1A-1H describe the catheter 10 of the present invention providedwith a thin, puncturable cover 102 over the guidewire lumen 18.Typically, catheter 10 may include devices such as a catheter balloon 20and/or stent 21 at its distal end 17 and a hub 14 at the proximal end16. As shown by FIGS. 1A-1H, the thin, puncturable cover 102, in thisinstance a thin-walled a thin tubular sheath 13 (forming guidewire lumen18) designed to be punctured by the back end of a guidewire 19, may beplaced coaxially about the inflation lumen 22. The length of the thintubular sheath 13 may extend over all or part of the length of cathetershaft.

After feeding guidewire 19 through the distal section of the guidewirelumen 18 and into the thin-walled tubular sheath 13, the physician maychose any desired location along the length of thin-walled tubularsheath 13 at which to puncture the thin, puncturable cover 102 with theguidewire 19. In this fashion the physician may select his preferredlength of the guidewire lumen 18.

FIG. 1A shows a longitudinal cross section of a catheter 10 having apuncturable guidewire lumen covering 102, while FIG. 1B shows alongitudinal cross section of the catheter of FIG. 1A in use with theguidewire 19, the guidewire having punctured the puncturable covering102. FIGS. 1C and 1D show, respectively, transverse cross sections ofthe catheter of FIG. 1B with the guidewire 19 within and outside of thepuncturable section 102.

FIG. 1E shows a longitudinal cross section of a catheter that is avariation of the design shown in FIGS. 1A and 1B wherein the guidewireoperates in a slot 104 provided in the exterior wall of a lumen of thecatheter. It is apparent that the thin, puncturable cover 102 may beprovided only over this slot portion and is not required to enclose theentire circumference of the inner catheter. FIGS. 1F, 1G and 1H showtransverse cross sections taken at three different locations along thelength of the catheter shown in FIG. 1E.

The puncturable guidewire lumen may be made in a variety of ways.

In a preferred embodiment, catheter 10 including inflation lumen 22 andguidewire lumen 18 is made using a catheter shaft 15 as shown in theperspective view of FIG. 2A wherein guidewire lumen 18 is in the form ofa slot 104. The catheter shaft 15 may be made in this form by extrusion(using any known polymeric material suitable for the application), ormay alternatively be extruded with fully enclosed lumens and then havethe extruded material covering the guidewire lumen skived away.Preferred materials will be of a color offering good contrast with theoperational field, and most preferably are fluorescent orphosphorescent.

Optionally, such a catheter shaft may be stiffened along all or part ofits length as necessary by the inclusion of stiffening wires runningparallel to the longitudinal axis of the catheter, or by adding atubular metal reinforcing braid to the catheter shaft, or by inserting alength of metal hypotube, tubular braid or helically wound wire into theinflation lumen 22. These stiffening methods may be used in combinationif desired. For simplicity, these well-known stiffening methods are notshown in the figures.

If it is desired to use a hypotube to stiffen only a portion of thelength of the catheter shaft, it may be desirable to cut ahelically-oriented slot through the wall of the end of the hypo tubethat will be located within the length of the catheter shaft to reducethe abrupt stiffness transition of the stiffened section to theunstiffened section.

As shown by the perspective view of FIG. 2B, the slotted catheter shaft15 is provided with a helically-wrapped covering of tape 24. Preferably,the wrapping is applied in two layers wherein adjacent wrappings haveoverlapping edges and the second layer is applied over the first with anopposite pitch, meaning that the two wrappings are applied beginningfrom opposite ends of the catheter shaft 15. The use of the two layersof tape 24 wrapped from opposing directions results in a strong coveringthat is resistant to tearing following puncture by the guidewire backend.

While a variety of thin, flexible polymer materials such aspolyethylene, polypropylene, polyamide, polyethylene terephthalate, etc.may be used for the tape 24. Porous polymers, optionally provided with athin, non-porous coating, may be advantageously used because of theirexcellent flexibility. Tape 24 is most preferably made from a thinporous expanded PTFE (ePTFE) film that has been provided with a porousor non-porous coating of a thermoplastic such as a thermoplasticfluoropolymer, preferably fluorinated ethylene propylene (FEP). ePTFEfilms are generally made as taught by U.S. Pat. Nos. 3,953,566 and4,187,390 to Gore. Most preferred ePTFE films for the presentapplication are taught by U.S. Pat. No. 5,476,589 to Bacino. Theconstruction of thin, helically-wrapped tubes from ePTFE films andthermoplastic-coated ePTFE films, and the method of providing thecoating onto the ePTFE films, are taught by U.S. Pat. No. 6,159,565 toCampbell et al.

An example of a helically-wrapped catheter shaft as shown by FIG. 2B wasmade using an FEP-coated ePTFE tape. The tape had a width of about 6 mmand a thickness of about 0.005 mm. The ePTFE had mean fibril length ofabout 50 microns and a bulk density of about 0.5 g/cc. The ePTFE filmwas provided with a non-porous coating of FEP on one side. After thecoated film was cut into a narrow tape, the tape was helically wrappedonto a stainless steel mandrel of diameter larger that the outsidediameter of the chosen catheter shaft. The first layer of the wrappingwas applied with the FEP coated side of the tape facing away from themandrel and the second layer was wrapped in the opposite direction fromthe first with the coating facing toward the mandrel and first layer.The wrapped mandrel was then heated for about 8 minutes in a convectionoven set at 320° C. to melt-bond the helically-wrapped layers of thetube together. Following removal from the oven and cooling to about roomtemperature, the helically-wrapped tube was removed from the mandrel andfitted over a length of the desired catheter shaft 15 that was shorterthan the length of the helically-wrapped tube. The opposite ends of thehelically wrapped tube were gripped using pliers and tension was appliedto cause the helically-wrapped tube to elongate and reduce in diameter,thereby tightly conforming to the outer surface of the catheter shaft.The ends of the helically-wrapped tube were adhered to the outer surfaceof the catheter shaft using a cyanoacrylate adhesive. The ends of thecovered catheter shaft 15 were then transversely cut to the desiredlength with a sharp blade. If desired, the hub component typicallyfitted to the proximal end of the catheter shaft may be fitted over thehelical wrap.

The thickness of the thin tubular tape covering 102 was determined to beabout 0.012 mm by measuring the diameter of the catheter shaft at 90degrees to the orientation of the slot 104 using a laser micrometer bothbefore and after the application of the helically-wrapped covering.

The covered catheter 10 that resulted from this process retained thegood flexibility of the precursor catheter shaft 15 prior to covering.When a guidewire 19 was inserted into the guidewire lumen 18, the thincover 102 exhibited good transparency, meaning that the back end of theguidewire 19 was visible to the unaided eye as it passed through thelength of the guidewire lumen 18. It was not difficult to stop theprogression of the guidewire back end at a desired point along thelength of the guidewire lumen, and by bending the catheter with theguidewire slot oriented to the outside of the bend, the covering 102 wasreadily punctured by the back end of the guidewire 19. When a largeportion of the length of the guidewire was pulled through the puncturesite, the puncture site exhibited no sign of tearing or of appreciableenlargement of the puncture.

FIG. 2C is a perspective view of a catheter 10 including a tubularsheath 13 for use as the thin puncturable cover 102 over slot 104. Thesheath may be in the form of a thin extruded tube of, for example, PET.It may be applied similarly to the above-described helically-wrappedtube using a tubular sheath 13 of slightly larger inside diameter thanthe outside diameter of the catheter shaft 15 to be covered. The outersurface of the catheter shaft 15 may be provided with a thin coating ofa suitable adhesive if desired, after which the thin tubular sheath 13is fitted over the catheter shaft 15 and tensioned to cause it toelongate and reduce in diameter to conform to the outer surface of thecatheter shaft 15. Sheath 13 may also be made from a shrink tubing thatis heated after being fitted about the outer surface of the cathetershaft 15 to cause it to conform thereto.

FIG. 2D is a perspective view of the catheter 10 of FIG. 2C wherein thethin tubular sheath is formed by a cigarette wrap, wherein thebraid-covered catheter shaft is additionally covered by an adequatelylong strip of thin polymeric material that has a width equal to orslightly greater than the circumference of the braid covered cathetershaft. This strip is wrapped around the catheter shaft as shown andadhered by thermal bonding or by the use of a suitable adhesive.

Another alternative for the puncturable thin cover 102 is shown in theperspective view of FIG. 2E wherein a thin tape 24 is adhered to theouter surface of the catheter shaft 15 adjacent to the edges of slot104. In another embodiment, the guidewire lumen 18 may be extruded orotherwise formed to have an integral, thin, puncturable covering 102 asshown by the perspective view of FIG. 2F. FIG. 2G is a perspective viewof the catheter 10 of FIG. 2F wherein pre-formed openings 25 are formedthrough the thin puncturable cover 102 to allow passage of the back endof a guidewire through any pre-formed opening 25 chosen by the user. Itis apparent that these pre-formed openings 25 may be used with many ofthe various described embodiments.

FIGS. 3A-3C show transverse cross sectional views that represent avariation on the embodiment of FIG. 2E. As shown by FIG. 3A, tape cover24 may be provided so as to increase the space available in theguidewire slot 104 by applying the tape so that it bridges the slot withadditional tape width, resulting in the raised aspect shown by this thinpuncturable cover 102. This can allow for the use of a larger guidewireif desired. When slot 104 is unoccupied by a guidewire, the thin andflexible tape 24 may take on a non-uniform appearance, giving theguidewire lumen and thin puncturable cover 102 an irregular crosssection as shown by FIGS. 3B and 3C. It is apparent that the appearanceof each of these three transverse cross-sections may exist at differentlocations along the length of the same catheter.

The puncturable cover 102 may also be made using threads, wires or otherfilaments. For example, threads may be wound around a slotted cathetershaft 15 in various desired patterns to form a covering over a guidewirelumen 18 that effectively contains a guidewire 19 but allows the backend of the guidewire to be passed through any of the multiplicity ofspaces between adjacent threads of the wrapped covering. The threadsmay, for example, be provided as a helically-wrapped pattern, a braidedpattern or a knit (e.g. warp knit) pattern. By orienting the threads inclose proximity to one another, the guide wire will preferentially staywithin a lumen of which the thread defines a portion of the wall.However, the end of the wire can be maneuvered to exit this lumenbetween the threads. By using a wound thread, the structure is neverdamaged allowing the catheter to be reused multiple times. Bycontrolling the spacing between adjacent threads, the ease of which theend of the wire exits the lumen may be altered. Preferentially, smalldiameter threads can be used, for example, with diameters from 0.012 to0.5 mm. Any variety of thread materials may be used, included commonthermoplastic (e.g., polyamide, polypropylene, polyester, etc),thermosets, fluoroplastics (e.g., ePTFE) or various metal wiresincluding stainless steels and nitinol.

As shown by the perspective view of FIG. 4A, a catheter shaft 15 isover-braided with filaments 31. The braid may have numerousconfigurations including, but not limited to, number of filaments, pickcount and pitch angle. As well, filaments 31 may be of various crosssections such as round, square or rectangular.

FIG. 4B shows a preferred embodiment wherein catheter 10 of FIG. 4A isprovided with an outer sheath 13 applied over catheter shaft 15 andbraid 31 and attached by any of various methods such as heat oradhesive. Following the addition of sheath 13, an appropriately-sizedmandrel is inserted into the guidewire lumen 18. The catheter is mountedin a laser (e.g., a 20 watt CO² laser, Applied Laser Technology,Beaverton Oreg.) with the laser beam directed to slot 104. The laser isused to ablate the polymer material of sheath 13 covering slot 104 alongthe desired length of the catheter 10, resulting in cutaway slot 33through sheath 13 exposing slot 104 beneath braid 31. The laser powerparameters are such that the polymer material of sheath 13 is ablatedyet metallic braid filaments 31 are left undamaged. The indwellingmandrel effectively blocks the laser energy from damaging the oppositeside of the catheter shaft 15. The resultant catheter 10 is left with abraided underlying chassis and an outer polymer sheath 13 in which a“strip” of braid is exposed directly above slot 104, whereby guidewirelumen 18 lies immediately below the exposed strip 33 of braid 31. Aclinician may then use the back end of a guide wire to part the braidfilaments at any suitable user-defined position along this strip 33,thus exiting the guidewire from catheter 10 through the selectedinterstice of braid 31.

FIG. 4D describes an alternative embodiment whereby a braided tube 37 isprocured, this tube having an outside diameter corresponding to theinside diameter of slot 104 of catheter shaft 15. The braided tube 37 ismade to have a suitable inside diameter to provide adequate clearancefor passage therethrough of an intended guidewire. Braided tube isfitted into slot 104 by interference, or by joining with an adhesive. Inuse, as with the previously described braided construct, the guidewiremay be passed through any desired interstice of the braid 31 to exitcatheter 10.

FIG. 4E describes a variation of FIG. 4A wherein braid 31 is replaced byhelically wound filament 41, which may be of polymeric or metallicmaterial. FIG. 4F shows an alternative to FIG. 4D wherein braided tube37 is replaced by helically wound tube 47. Again, the helically woundtube may be of polymeric or metallic material. The embodiments of FIGS.4E and 4F are desirable in that the space between adjacent helicalwindings will widen when the catheter shaft is bent with the exposedwinding on the outside of the bend, making it easier to pass the backend of a guidewire through any desired space between adjacent helicalwindings.

FIG. 4G is a perspective view of an alternative embodiment to thoseshown by FIGS. 4D and 4F wherein tube 49 inserted into slot 104 is madefrom a thin polymeric material. This tube is preferably made byhelically wrapping a thermoplastic-coated ePTFE film about a mandrel ofsuitable size, bonding the wrapping together to result in a cohesivetube, inserting the tube and mandrel into slot 104 and finally removingthe mandrel. Alternatively if desired, the mandrel may be removed fromwithin the tube prior to insertion of the tube 49 into slot 104.

FIG. 5 shows a longitudinal cross section of an alternative embodimentof catheter 10, including a hub 14 on the proximal end 16 of theinflation lumen 22. In this embodiment, catheter 10 is provided with apuncturable adjustable length guidewire lumen 18 that is in the form ofa thin tubular sheath 13 puncturable by guidewire 19 as shown. A tubularslider 24 is used in place of a conventional y-fitting, distal to hub 14for attachment and control of the proximal end of the adjustable lengthguidewire catheter lumen 18. Adjustable length guidewire catheter lumen18 is shown in its axially compressed or shortened state. Tubular slider24 is provided with only a small clearance between the inner diameter ofslider 24 and the outer diameter of the inflation lumen 22. Adjustablelength guidewire catheter lumen 18 may be made from a variety of thin,flexible polymer materials such as polyethylene, polypropylene,polyamide, polyethylene terephthalate, etc. Porous polymers, optionallyprovided with a thin, non-porous coating, may be advantageously usedbecause of their excellent flexibility. Adjustable length guidewirecatheter lumen 18 is preferably made from a porous expanded PTFE (ePTFE)film that has been provided with a porous or non-porous coating of athermoplastic fluoropolymer as described previously.

The thin-walled tube is preferably made from an FEP-coated ePTFE filmthat has been cut into a tape (width, e.g., 12.7 mm) and helicallywrapped on a mandrel with the FEP coating placed on the exterior of thewrapping. The helically wrapped tube is then placed into an oven for asuitable time (e.g., 8 minutes in an oven set at a temperature of 320°C.) to thermally bond the overlapped edges of the helical wrappingtogether, thereby forming a coherent tube. After removal from the ovenand cooling, the resulting tube is removed from the mandrel and may beused as the adjustable length lumen component in the catheter of thepresent invention. The ends of this tube may be joined to the adjacentcomponents by overlapping the tube end over the adjacent component andadhering the overlapped areas with an adhesive such as a cyanoacrylate(e.g., Loctite 401, Rocky Hill, Conn.) or an ultraviolet adhesive (e.g.,Loctite 3311). Alternatively, the tube may be everted to orient theFEP-coating toward the lumen, and an adequate heat source may be used tomelt-bond the FEP coating to catheter components such as metalhypotubes.

For use as the puncturable, adjustable length lumen tubular component ofa catheter, the ePTFE tube may be provided with corrugations (e.g,accordion pleats or folds) with various methods such as those taught byU.S. Pat. No. 3,105,492 to Jeckel and U.S. Pat. No. 6,016,848 to Egres,Jr. Alternatively, it is not required to provide the thin-walled tubewith preformed corrugations as, during axial compression from the fullyextended length to the shortened, fully compressed length, the tube willwrinkle and corrugate in a non-uniform but entirely suitable manner foruse as the adjustable length lumen portion 18 of catheter 10. In anotheralternative, an elastomer may be used for the adjustable length portion18 that would be in its relaxed state prior to loading over theguidewire and would extend into a tensioned condition when the distalend of the catheter is advanced.

Longitudinally extruded and expanded tubes of PTFE, that is, seamlessePTFE tubes, may be used in thinwall form as the puncturable, adjustablelength guidewire catheter lumen. Under axial compression, theinterconnecting fibrils of the node-and-fibril microstructure of ePTFEwill progressively bend and fold. This allows the tubular material toaxially compress in a substantially uniform fashion, retaining thelongitudinal uniformity of the tube wall (macroscopically), withoutcorrugations. This bending of the fibrils within the microstructure ofthe wall of the ePTFE tube during axial compression is described in U.S.Pat. No. 4,877,661 to House et al. Longer mean fibril length tubes arepreferred to maximize the compressible length, e.g., ePTFE tubes ofabout 50 micron or greater mean fibril length.

A catheter having a puncturable, adjustable length guidewire lumen wasconstructed using a very thin walled (e.g., 0.03 mm) sheath material.The sheath material is required to be thin enough to corrugate in smallfolds, allowing the length of the sheath to be reduced to less than 50%of its original length by compressing into the small amplitude folds. A0.01 mm thick ePTFE film provided with a non-porous FEP coating on oneside was chosen for the sheath material. This film was slit to a 6.4 mmwidth, thereby forming a tape.

An ePTFE tube, having an inner diameter of about 1.6 mm and a wallthickness of about 0.13 mm, was fitted over a 1.6 mm diameter stainlesssteel mandrel having a length of about 180 cm. The 6.4 mm wide tape wasthen helically wrapped about the outer surface of the ePTFE tube with a50% overlap, resulting in a helically-wrapped tube covered with twolayers of tape. The resulting assembly was then placed into an airconvection oven set at 320° C. for 8 minutes, after which it was removedfrom the oven and allowed to cool in an ambient environment.

After cooling, the helically-wrapped tube was removed from the mandrelby withdrawing the mandrel from the tube. The end of the extruded tubethat had not been helically-wrapped was clamped in a vise. The end ofthe helical wrapping closest to the vise was simultaneously pinched onopposite sides of the tube using the thumb and forefingers of bothhands, and the helical-wrapping was stripped from the underlying ePTFEtube by everting the helically-wrapped tube while pulling it away fromthe vise.

This thin-walled tube had an approximate wall thickness of 0.03 mm(measured using Mitutoyo Snap Gauge, Model #1D-C112EBS) and an innerdiameter of approximately 1.7 mm (measured using a certified minus pingauge with a tolerance of 0.01 mm). When this tube was loaded on a 1.2mm diameter mandrel, it was able to be easily compressed to about 5% ofits original length using light digital pressure.

Continuing assembly of the catheter, this sheath was then coaxiallymounted over a conventional Percutaneous Transluminal CoronaryAngioplasty (PTCA) catheter with a maximum outer diameter proximal ofthe balloon of less than approximately 0.040″ (1.02 mm). The PTCAcatheter used was a rapid exchange type, having a proximal guidewireexit port at a location significantly distal of its hub. Prior tomounting the sheath, a 9 Fr (3.0 mm) inner diameter hemostasis y-armvalve (P/N 80348, Qosina, Edgewood, N.Y.) was slid onto the catheterfrom the catheter's distal end (hemostasis valve oriented away from theback end of the catheter). Next, a female luer (P/N 65206. Qosina,Edgewood, N.Y.) was slid onto the catheter and the luer connection ofthese two components was engaged. A 2.0 mm inside diameter by 2.1 mmoutside diameter 304 stainless steel tube (Microgroup, Medway, Mass.)was then swaged down to approximately 1.4 mm inside diameter by 1.6 mmoutside diameter, and then trimmed to a length of approximately 19 mm.

This tube was slid coaxially over the catheter and bonded to the distalend of the female luer with an approximate 6 mm overlap usingcyanoacrylate adhesive (Loctite 401, Loctite Corp., Rocky Hill, Conn.).Next, the helically-wrapped sheath described above was slid over thedistal tip of the catheter and its proximal end attached by sliding itover the exposed end of the hypotube. These overlapped surfaces werebonded using the cyanoacrylate adhesive, after which 2.3 mm insidediameter polyolefin 2-to-1 shrink ratio shrink tubing was fitted overthe junction and heated to conform to the surface of the junction. Thedistal end of the sheath was then trimmed to a length of approximately135 cm, equal to the desired working length of the catheter (i.e. lengthfrom the distal tip of the catheter to the distal end of the strainrelief on the catheter's hub). The distal end of the sheath was thenattached at a location approximately 2 mm distal of the proximalguidewire port in the wall of the PTCA catheter. This attachment wasmade using the cyanoacrylate adhesive between the sheath and catheter,and then over-wrapping this attachment point with cyanoacrylate adhesiveand 0.13 mm diameter ePTFE suture (CV-8, WL Gore and Associates,Flagstaff, Ariz.).

To complete the catheter a hemostasis y-fitting was slid distally on thecatheter until it was just proximal of the proximal hole of the originalPTCA catheter. This compressed the sheath to approximately 15% of itsoriginal approximately 135 mm length. A guidewire was then fed into thedistal tip of the catheter and carefully threaded through the catheter,including the sheath component, and out from the proximal end of thecatheter through the side arm of the y-fitting.

With the guidewire inserted, the user was able to hold the guidewire andhemostasis y-fitting in a fixed position while advancing the distal tipof the catheter relative to the guidewire. Compared to a standardcatheter with a proximal guidewire side port fixed distally of theproximal hub, this inventive catheter significantly improved the abilityof the section of the catheter, distal to the hemostasis y-fitting, totrack the guidewire and allow push forces applied to the proximalportion of the catheter shaft to be transferred directly to the distaltip of the catheter.

FIG. 6 is a perspective view of catheter 10 in use with a puncturingtool 63 that enables puncturing of the cover 102 by the back end ofguidewire 19. While such a tool is deemed unnecessary for manyapplications, for others it may prove advantageous. As shown, tool 63 issimply a short length of tubing that may be either polymeric tubing ormetallic tubing. It is most easily made by bending the short length oftubing (before it is fitted about a catheter) and cutting away a portionof the wall along one side of the tube in the region of the middle ofthe length of the tube, resulting in opening 62. In use, tool 61 isfitted coaxially about catheter 10 and moved along the length ofcatheter 10 to the location at which it is desired to puncture cover 102with the back end of guidewire 19. The tool 61 is oriented so that theopening 62 exposes cover 102 on the side of the catheter where theguidewire is or will be contained. When a guidewire 19 is inserted intothe catheter 10 to the location at which it is desired to puncture thecatheter, with this location exposed at opening 62 in tool 61, both thecatheter 10 and tool 61 are bent as shown by FIG. 6. This bendingresults in puncturing of cover 102 by the back end of guidewire 19. Thebending of catheter 10 is the result of force applied at three points63, with the middle point being on the inside of the bend along themiddle of the length of the bend and the two outer points being on theoutside of the bend at the two opposite ends of the bend. It is apparentthat the tool may take any suitable form that provides this three pointcontact during bending wherein the act of bending enables or results inpuncturing of cover 102 at the desired location by the back end ofguidewire 19. Following puncture, the tool is moved out of the way bysliding it coaxially along the length of the guidewire.

While the principles of the invention have been made clear in theillustrative embodiments set forth herein, it will be obvious to thoseskilled in the art to make various modifications to the structure,arrangement, proportion, elements, materials and components used in thepractice of the invention. To the extent that these variousmodifications do not depart from the spirit and scope of the appendedclaims, they are intended to be encompassed therein.

1. A catheter assembly comprising a flexible catheter shaft having alength and an outer surface, and having at least one longitudinallyoriented slot extending along at least a portion of the length of saidcatheter shaft, wherein said slot is provided with an outer coverconsisting essentially of a helically wrapped porouspolytetrafluoroethylene tape whereby said covered slot provides a lumenextending along the portion of the length of the catheter shaft, saidcover adhered to the outer surface of the catheter shaft adjacent to theslot, said cover being puncturable at multiple points along the lengthby the back end of a guidewire, said cover being resistant to tearing bythe guidewire at a puncture site following having been punctured by theguidewire.
 2. A catheter assembly according to claim 1 wherein saidhelically wrapped tape comprises two layers with the two layers appliedat different wrap angles.
 3. A catheter assembly according to claim 1wherein said porous polytetrafluoroethylene is provided with anon-porous coating.
 4. A catheter assembly according to claim 3 whereinsaid cover is translucent.
 5. A catheter assembly according to claim 1wherein said cover is translucent or transparent wherein a guidewirelocated within the slot is visible through the cover.
 6. A catheterassembly according to claim 1 wherein said lumen is a guidewire lumen.7. A catheter assembly according to claim 1 wherein said lumen extendsfor most of the length of the catheter.
 8. A catheter assembly accordingto claim 1 wherein said lumen extends for all of the length of thecatheter.